Urinary problems can have serious consequences, particularly when the problem is one of retention, incomplete emptying, or dysuria. Urine flow problems include urine retention, incontinence, and difficult urination. Retention can result from any of a number of causes, including without limitation, spinal cord injury, typhoid, peritonitis, prostatic enlargement, urethral stricture, urethritis, cystitis, bladder tumors, or urethral calculus. Patients suffering from these and other conditions often require some interventional means to periodically drain or augment drainage of the bladder. Failure to do so can result in damage of the epithelium and detrusor muscles associated with the bladder, and an increased potential for bacterial invasion which is commonly thought to contribute to urinary tract infection potentially leading to life-threatening kidney failure.
Beyond notions of intervention, in roads are presently being made in the area of office and office/home based monitoring of patients for purpose of diagnosing the contribution of the prostatic urethra to the outflow urodynamics. Differential diagnosis is understood by accepting that there are three primary anatomical organs which interact to contribute to the function of urination. First the bladder, second the urethra, and third the sphincter(s). The prostatic gland surrounds the urethra in the very short segment between the bladder, at its outlet, and the external sphincter. When the patient experiences symptoms of bother which may be made manifest in several independent or co-existing difficulties during urination, treatment is often sought.
For example, bothersome symptoms might include: (i) incomplete emptying, (i.e., the patient is only able to urinate small volumes, e.g. <100 milliliters (ml), or has an elevated volume of urine left in the bladder following urination, e.g. >100 ml. per attempt); (ii) frequent urges to urinate (i.e., experiencing a frequent feeling of needing to urinate by an individual); (iii) intermittency (e.g. a patient's flow stops and starts often during urination); (iv) has a very weak and inconsistent urine flow stream; (v) stress incontinence (e.g. leaking during lifting or straining as a result of excessive urine in the bladder or weakened sphincters. With the exception of stress incontinence, each of these may contribute to nocturia (i.e., poor sleep due to the repeated need to urinate during the night), yet a further symptom.
Up to two million office visits annually in the United States are attributed to patients being bothered by some form of lower urinary tract symptoms (LUTS). As previously noted, there are two primary organs, and the prostate, involved with the event of urination. The symptoms are virtually always suspected to be caused by the intrusion of an enlarged prostate gland upon the urethra, however, symptoms are often caused by irregularities in bladder function, or sphincter deficiencies. For this reason, bladder outlet obstructions (BOO) is a major subgroup of LUTS. In men between the ages of 55 and 75 years, it is estimated that between 50 and 75% have some degree of bladder outlet obstruction, however, it may not be responsible for their symptoms.
Bladder outlet obstructions are primarily caused by the enlargement of the prostate gland (e.g., benign prostate hyperplasia (BHP)) which results in radial compression of the urethra surrounded thereby (i.e., the prostatic urethra), thus obstructing (i.e., constricting) urine flow, resulting in incomplete emptying of the bladder (i.e., there being what is clinically referred to as a “post void residual” (PVR) remaining in the bladder). Heretofore, males presenting with LUTS have few diagnostic options prior to either long term pharmacological, or invasive irreversible medical procedures such as trans urethral resection of the prostate (TURP), or non-surgical procedures such as thermal treatment of the prostate.
It is well known within the urological community that significant numbers of men undergoing treatment for prostate disease have sub-optimal results. According to Bruskewitz, benign prostatic hyperplasia(BPH) can be discussed in terms of prostatic enlargement, outlet obstruction and lower urinary tract symptoms (LUTS). Jepsen J. V. and Bruskewitz R. C., Comprehensive Patient Evaluation for Benign Prostatic Hyperplasia, 1998, Urology 51 (A4):13–18. In addition to the usual factors believed to lead to prostate induced LUTS (e.g., enlarged prostate and increased prostate muscle tone) other conditions of the lower urinary tract impact male voiding and need to be considered. Bruskewitz stated that a large part of the symptomotology of BPH might be explained by bladder dysfunction.
Bladder conditions that are prevalent in men with LUTS, either separately or in combination with outlet obstruction, include detrusor instability and detrusor hypocontractility. Kaplan S. A. and, Te A. E., Uroflowmetry and Urodynamics, 1995, Urologic Clinics of North America 22 (2):309–320. In a population of 787 men with symptoms of prostatism, Kaplan found that 504 (64%) had demonstrable prostatic urethral obstruction, of which 318 had concomitant detrusor instability. In the group, 181 had detrusor instability as their sole diagnosis. Impaired detrusor contractility was present in 134 (17%) and 49 of these had impaired detrusor contractility as their only diagnosis. Bruskewitz and others have also shown that a significant number of men with LUTS, including those who receive definitive treatment, are unobstructed. Abrams P., In Support of Pressure Flow Studies for Evaluating Men with Lower Urinary Tract Symptoms, 1994, Urology 44 (2): 153–55. Patient satisfaction rates after definitive prostate treatment vary from 100% to 75% or less. In some cases the lack of success may be related to unidentified bladder dysfunction. Bruskewitz concluded that bladder dysfunction should receive more attention (in the evaluation and treatment of LUTS) and better measures should be developed to quantify it. Presently, urodynamic methods to assess bladder outlet obstruction generally include uroflow testing, pressure flow testing and general patient history/examination.
Uroflow testing provides information about the combined contribution of the detrusor and urethra to uroflow. The limitation of uroflow testing is that it is not possible to determine with certainty in all cases whether a low flow and a poor voiding pattern are secondary to outlet obstruction, detrusor hypocontractility or a combination thereof. Further, the test can be problematic because it is only a single event that can be influenced by patient factors such as anxiety and performance of the test (i.e. direction of the urine steam into the collecting reservoir). Abrams found that the success rate was only 70% when uroflow was used to select patients for surgery. Abrams P. H., Prostatism and Prostatectomy: The Value of Flow Rate Measurement in the Preoperative Assessment for Operation. J. Urol 1977, 177:70–71.
Pressure flow testing can be used to define outlet obstruction and, in addition, provides information about the contractility and performance of the bladder. The pressure flow test, however, is not much more successful in predicting success of treatment, as defined by the patient, than uroflow (75% v 64%). Jepsen J. V. and Bruskewitz R. C., Comprehensive Patient Evaluation for Benign Prostatic Hyperplasia, 1998, Urology 51 (A4):13–18. Therefore the urological community as well as the Agency for Healthcare Policy & Research (AHCPR) do not find justification for its routine use.
Finally, the standard work-up of patients with LUTS being evaluated for bladder outlet obstruction generally consists of history and physical examination, including assessment of prostate volume, PSA, uroflow testing, quality of life, and symptom and bother index. Based on the results, treatment decision are made. Using these evaluations underlying problems with bladder function cannot be detected.
In lieu of traditional urodynamic test methodologies such as the use of video urodynamics simultaneously with the holding and release of urine, cystometry, urethral pressure profiling, ultrasonic volume assessments (i.e., PVR), and uroflowmetry, each of which address the filing/emptying conditions (i.e., dynamics) of the bladder, endourethral devices and accompanying methodologies have been developed specifically to ascertain the nature of the BOO. For instance by permitting the structures of the lower urinary tract to physiologically act in a sequential and incremental manner upon portions of a device during a natural micturition event, an observable change in fluid dynamics in furtherance of lower urinary tract symptoms diagnosis may be noted.
Devices have been developed to be positioned in the urethra and/or bladder to correct the problems of urine flow. Problems and disadvantages of heretofore known devices include the deleterious effects (i.e., pitting, depositions, etc.) associated with the urethral environment upon critical device components (e.g., valve actuators, flow conduits, etc.) which at a minimum render such devices less effective, and which at a maximum, cause device component failure or render the device wholly ineffective, which necessitates emergent removal and, as the case may be, urinary tract damage repair. Problems of device leakage, or less than complete emptying of the bladder are also widely known. Furthermore, issues surrounding device deployment and fit, positioning, repositioning, and retention (i.e., sufficient anchoring) have also been well documented.
It is especially critical that the endourethral device be stable with respect to position (i.e., a physiologically properly deployed and stable position), and comfortable to wear, as the urinary tract is sensitive to contact. Inter-urethral stents have been utilized within the male urethra within the prostatic region with many users foregoing such devices for alternate therapies due to feelings of discomfort and/or pain. Many endourethral devices have similarly been evaluated for urinary incontinence for females. Based upon clinical findings, many have been shown to be uncomfortable, thus severely retarding their utility as a therapy. Other devices have migrated into the bladder, or have been expelled under straining conditions.
Furthermore, it is imperative that the device be no more invasive as is necessary. For instance, it is advantageous that the device minimally engage the structures of the lower urinary tract, particularly in accomplishing an anchoring function. For example, it is well known that secretions of the prostatic urethra, including the Cooper's gland, whether during sexual function or otherwise, is clinically beneficial, the secretions are comprised, in part, of antimicrobial agents which assist in the prevention of urinary tract infections. It is further believed that bathing of the bladder neck with urine assists infection prevention. Generally, flow of urine external of an endourethral device permits the free passage of urinary tract fluids from the urethra as urine is released, thereby allowing a more physiologically normal urine discharge. Thus, whether it be a short or long term endourethral device, for interventional, diagnostic or other purpose, stable anchoring in combination with physiologically proper, non-traumatic device deployment and retention is essential.